CUCM Third−Party CA−Signed LSCs Generationand Import Configuration Example

Document ID: 118779

Contributed by Ramesh Balakrishnan, Cisco TAC Engineer.Mar 09, 2015

Contents

IntroductionPrerequisites Requirements Components UsedConfigure Upload the CA−Root Certificate Set Offline CA for Certificate Issue to Endpoint Generate a Certificate Signing Request (CSR) for the Phones Get the Generated CSR from the CUCM to the FTP (or TFTP) Server Get the Phone Certificate Convert .cer to .der Format Compress the Certificates (.der) to .tgz Format Transfer the .tgz File to the SFTP Server Import the .tgz File to the CUCM Server Sign the CSR With Microsoft Windows 2003 Certificate Authority Get the Root Certificate from the CAVerifyTroubleshoot

Introduction

Certificate Authority Proxy Function (CAPF) Locally Significant Certificates (LSCs) are locally−signed.However, you might require phones to use third−party Certificate Authority (CA)−signed LSCs. Thisdocument describes a procedure that helps you achieve this.

Prerequisites

Requirements

Cisco recommends that you have knowledge of Cisco Unified Communication Manager (CUCM).

Components Used

The information in this document is based on CUCM Version 10.5(2); however, this feature works fromVersion 10.0 and later.

The information in this document was created from the devices in a specific lab environment. All of thedevices used in this document started with a cleared (default) configuration. If your network is live, make surethat you understand the potential impact of any command.

Configure

Here are the steps involved in this procedure, each of which is detailed in its own section:

Upload the CA−Root Certificate1. Set Offline CA for Certificate Issue to Endpoint2. Generate a Certificate Signing Request (CSR) for the Phones3. Get the Generated CSR from Cisco Unified Communications Manager (CUCM) to the FTP Server4. Get the Phone Certificate from CA5. Convert .cer to .der Format6. Compress the Certificates (.der) to .tgz Format7. Transfer the .tgz file to the Secure Shell FTP (SFTP) Server8. Import the .tgz File to the CUCM Server9. Sign the CSR With Microsoft Windows 2003 Certificate Authority10. Get the Root Certificate from the CA11.

Upload the CA−Root Certificate

Log into the Cisco Unified Operating System (OS) Administration web GUI.1.

Navigate to Security Certificate Management.2.

Click Upload Certificate/Certificate chain.3.

Choose CallManager−trust under Certificate Purpose.4.

Browse to the CA's root certificate and click Upload.5.

Set Offline CA for Certificate Issue to Endpoint

Log into the CUCM Administration web GUI.1.

Navigate to System > Service Parameter.2.

Choose the CUCM Server and select Cisco Certificate Authority Proxy Function for the Service.3.

Select Offline CA for Certificate Issue to Endpoint.4.

Generate a Certificate Signing Request (CSR) for the Phones

Log into the CUCM Administration web GUI.1.

Navigate to Device Phones.2.

Choose the phone whose LSC must be signed by the external CA.3.

Change the Device security profile to a secured one (if not present, add one system on the SecurityPhone Security profile).

4.

On the phone configuration page, under the CAPF section, choose Install/Upgrade for theCertification Operation. Complete this step for all of the phones whose LSC must be signed by theexternal CA. You should see Operation Pending for the Certificate Operation Status.

5.

Phone Security profile (7962 model).

Enter the utils capf csr count command in the Secure Shell (SSH) session in order to confirm whethera CSR is generated. (This screen shot shows that a CSR was generated for three phones.)

Note: The Certificate Operation Status under the phone's CAPF section remains in the OperationPending state.

Get the Generated CSR from the CUCM to the FTP (or TFTP) Server

SSH into the CUCM server.1.

Execute the utils capf csr dump command. This screen shot shows the dump being transferred to theFTP.

2.

Open the dump file with WinRAR and extract the CSR to your local machine.3.

Get the Phone Certificate

Send the phone's CSRs to the CA.1.

The CA provides you with a signed certificate.

Note: You can use a Microsoft Windows 2003 server as the CA. The procedure to sign the CSR witha Microsft Windows 2003 CA is explained later in this document.

2.

Convert .cer to .der Format

If the received certificates are in .cer format, then rename them to .der.

Compress the Certificates (.der) to .tgz Format

You can use CUCM server's root (Linux) in order to compress the certificate format. You can also do this in anormal Linux system.

Transfer all of the signed certificates to the Linux system with the SFTP server.1.

Enter this command in order to compress all the .der certificates into a .tgz file.

tar −zcvf <file_name>.tgz *.der

2.

Transfer the .tgz File to the SFTP Server

Complete the steps shown in the screen shot in order to transfer the .tgz file to the SFTP server.

Import the .tgz File to the CUCM Server

SSH into the CUCM server.1.

Execute the utils capf cert import command.2.

Once the certificates are imported successfully, then you can see the CSR count become zero.

Sign the CSR With Microsoft Windows 2003 Certificate Authority

This is optional information for Microsoft Windows 2003 − CA.

Open Certification Authority.1.

Right−click the CA and navigate to All Tasks > Submit new request...2.

Select the CSR and click Open. Do this for all the CSRs.3.

All of the opened CSR display in the Pending Requests folder.

Right−click each and navigate to All Tasks > Issue in order to issue certificates. Do this for allpending requests.

4.

In order to download the certificate, choose Issued Certificate.5.

Right−click the certificate and click Open.6.

You can see the certificate details. In order to download the certificate, select the Details tab andchoose Copy to File...

7.

In the Certificate Export Wizard, choose DER encoded binary X.509 (.CER).8.

Name the file something appropriate. This example uses <MAC>.cer format.9.

Get the certificates for other phones under the Issued Certificate section with this procedure.10.

Get the Root Certificate from the CA

Open Certification Authority.1.

Complete the steps shown in this screen shot in order to download the root−CA.2.

Verify

Use this section in order to confirm that your configuration works properly.

Go to the phone configuration page.1.

Under the CAPF section, the Certificate Operation Status should display as Upgrade Success.2.

Note: Refer to Generate and Import Third Party CA−Signed LSCs for more information.

Troubleshoot

There is currently no specific troubleshooting information available for this configuration.

Updated: Mar 09, 2015 Document ID: 118779